Many different forms of exoskeletons have been developed to augment the strength of the user, augment the endurance of the user, facilitate locomotion of the user over differing terrains or to support a payload being carried by the user.
Although exoskeletons have broad potential use applications, there is increasing interest in the use of exoskeletons by soldiers to mitigate fatigue and injury associated with carrying high load burdens. However, if exoskeletons are to be successfully used by soldiers they need be relatively quiet during operation and importantly not impede normal movement or unduly increase the physical effort in taking such movement.
There are two basic types of lower extremity exoskeletons. The first type of exoskeleton is known as an ‘active’ exoskeleton. Active exoskeletons include some form of mechanical power generation device (e.g., motors and actuators) to carry the load and thereby increase the ‘carrying power’ of the user. However, such mechanical power generation devices require a power source that must also be carried by the user.
The second type of lower extremity exoskeleton is known as a ‘passive’ exoskeleton. Passive exoskeletons do not include any form of power generation device to carry the load. Rather they are intended to operate to mitigate fatigue and injury by transferring through rigid rods or linkages (sometimes referred to as “leg struts”) as much as possible of the user's backpack payload directly to the ground. Fatigue and injury mitigation is achieved because a proportion of any such payload is transferred directly to the ground bypassing the musculoskeletal system of the user. As the musculoskeletal system of the user is not subject to the transferred load, the user is less prone to fatigue and high load injuries.
U.S. Patent Application Publication No. 2012/0292361 teaches a backpack exoskeleton arranged to transfer the load of the backpack to the ground surface therefore reducing the effective weight of the backpack on the user. The right and left exoskeleton legs each include a thigh rod which is connected to a knee unit. The knee unit includes large and small knee wheels and bearings. The knee unit is provided to simulate the back and forth movement of the human knee. A bottom rod connects to the knee unit and extends all the way to the ground and bends underneath the arch of the user's shoe producing an arch rod. Hyperextension of the knee is prevented by a wheel stop that limits rotational movement of the bottom rod. Various points of adjustment are provided to ensure that the knee unit is located in line with the user's knee and to match the user's anatomy.
To date, typical lower extremity exoskeletons that have been developed, both active and passive, have not effectively reduced or matched the energy cost to the user. Furthermore, exoskeletons have not been accepted for use by soldiers. Many different problems with such exoskeletons have been identified. For example, the power supply used with active exoskeletons has a limited duration. During a military operation where a new power supply is not readily available or recharging not possible, the soldier must either discard the exoskeleton or continue to carry it. Discarding the exoskeleton is a relatively very expensive option and continuing to carry the exoskeleton is not advantageous because of the increased fatigue and injury risks.
Many soldiers are reluctant to wear exoskeletons because they are poorly integrated with the user and thus there is increased risk of the soldier becoming ‘snagged’ on foreign objects. This is particularly likely in dense terrain. Furthermore, existing exoskeletons are relatively cumbersome and thus restrict movement that may be needed particularly in an active situation. For example, a soldier wearing such an exoskeleton may have increased difficulty rolling and crawling.
Typical lower extremity exoskeletons are attached to the user at various points and are difficult to doff quickly if required.
For best performance, typical exoskeletons need to be calibrated to the individual user to match their anthropometrics. This is a relatively complex and lengthy process with lower extremity exoskeletons because the joint centres of the hip, knees and ankles must align with those of the exoskeleton. Accommodating the wide and ranging physical requirements of individual users with lower extremity exoskeletons may require increased cost, logistics and training.
Prior art lower extremity exoskeletons use rigid leg struts, multiple degree-of-freedom joints coupled to sensors and computers to mimic the human skeletal system and its kinematics. Matching human kinematics with an exoskeleton that is offset to the skeletal system is a very complex task and misalignment issues often cause unwanted forces that impair normal human kinematics and result in increased metabolic cost during locomotion. Trials by US Army Natick Soldier Centre have shown increases in metabolic cost of up to 40% using a lower extremity rigid-link exoskeleton (Gregorczyk et al. ‘Effects of a lower body exoskeleton device on metabolic cost and gait biomechanics during load carriage’, Ergonomics, Vol. 53, No 10, October 2010, pp. 1263-1275). Mass, especially distal mass, has been identified along with kinematic incompatibility as the other main cause of exoskeletons causing increased energy cost to the user.
The present disclosure seeks to provide in one aspect an improved lower extremity exoskeleton system. The present disclosure also provides in other aspects an item of clothing, and a length of fabric.
The discussion of the background to the disclosure herein is included to explain the context of the disclosure. This is not to be taken as an admission that any of the material referred to was published, known or part of the common general knowledge as at the priority date of this application.